Most plastics are based on synthetic organic macromolecules in which long chains of atoms, joined by covalent bonds, are formed by a replication of a simple group of atoms. These macromolecules can be linear, branched, spotted with sidechains, or crosslinked. Those macromolecules that are used in the formation of articles and are not crosslinked are called thermoplastics. Those macromolecules that are crosslinked are called thermoset.
Most plastics have been developed in the past century. These materials are often inert under all processes common to the environment and all digestion chemistries used by fauna and flora. For example, since living organisms have not evolved in the presence of the homopolymer of the methyl ester of 2-methyl-2-propenoic acid, [80-62-6], or the homopolymer of 1-ethenylbenzene, [100-42-5], they can not attack or digest these materials. This inert behavior has produced large accumulations of plastic in disposal sites such as landfills or marine dumping sites. Simultaneously, these inert solids kill large numbers of animals by trapping, entanglement or obstruction of the animal's digestive system. Blends of polysaccharides and plastics designed to relieve these problems are not acid/base stable and degrade only in that the polysaccharide component degrades within a year in the environment. The synthetic plastic component is environmentally stable. Thus, a need continues to exist for new thermoplastic and thermoset materials.